The development of hemoglobin-based oxygen carriers has focused on oxygen delivery for use in medical therapies such as transfusions and the production of blood products. Hemoglobin-based oxygen carriers can be used to prevent or treat hypoxia resulting from blood loss (e.g, from acute hemorrhage or during surgical operations), from anemia (e.g., pernicious anemia or sickle cell anemia), or from shock (e.g, volume deficiency shock, anaphylactic shock, septic shock or allergic shock).
Existing hemoglobin-based oxygen carriers include perfluorochemicals, synthesized hemoglobin analogues, liposome-encapsulated hemoglobin, chemically-modified hemoglobin, and hemoglobin-based oxygen carriers in which the hemoglobin molecules are crosslinked. Preparation of hemoglobin-based oxygen carriers includes several purification steps. Among the components that must be removed from collected blood is fibrinogen, which is a soluble protein that is converted into fibrin by the action of thrombin during clotting. Current techniques for processing blood often include addition of chemical agents, such as sodium citrate, to prevent coagulation. However, additional techniques which might, for example, reduce the expense of processing, without diminishing other qualities, such as ultimate product purity, are sought.